This invention relates to methods for producing flexible cable harnesses such as cable trees for motor vehicles, and to the resulting harnesses.
Cable harnesses having a treelike structure, known as cable trees, are made of a bundle of several electric cables and are used for the electrical connection of components, consuming devices and assemblies. The electric cables which are parallel to each other are bundled together with predetermined departures of cables from the bundle and preferably are fixed in a bundle by wrapping tape or by an insulating cover. The cable harness must be flexible and should be capable of being wrapped so that it is packable and readily transportable and, for placement and assembly in a motor vehicle, it should also be capable of being bent 90.degree.. With the increasing number of consuming and control devices in modem motor vehicles, the number, and in some cases the cross-section, of the cables to be connected in such a cable tree also increases and hence its flexibility decreases. Thus, the cable harness becomes increasingly rigid.
In order to prevent damage to the cables, complete enclosure of the cable harness is required. Complete but loose wrapping of the bundle, i.e., wrapping with low tensile force to assure adequate flexibility, can be obtained only by hand wrapping and leads to subjectively variable results with regard to wrapping thickness and strength. Wrapping machines, on the other hand, wrap with a high minimum tensile force, which leads to a very firmly wrapped and hence rigid cable harness.
In order to be able to wrap a cable harness mechanically and yet make it flexible, it has been sought to introduce into the cable harness, prior to wrapping, a blind cable in the form, for example, of a single cable of sizeable diameter or in the form of a wire having a non-adhesive coating, in particular a Teflon-coated wire, and, after mechanical wrapping of the harness, to withdraw the blind cable from the bundle, in order thereby to loosen the firmly and uniformly wrapped bundle of cables enclosed by the wrapping and increase the flexibility of the wrapped cable harness. This method has been found to have drawbacks. On the one hand, sticking of the blind cable to the wrapping tape or, with a blind cable having an anti-adhesion coating, sticking to adjacent cables, may occur which, in the latter case, may lead to damage of the cable insulation upon withdrawal of the blind cable and, on the other hand, makes withdrawal of the blind cable increasingly difficult with increasing length.